Many medical procedures, such as chemotherapy, intraveneous antibiotic therapy, and parenteral nutrition administration, require repeated and prolonged access to a patient's vascular system. Because it may be impractical or even dangerous to insert and remove a needle or catheter each time vascular access is needed in these applications, treatments requiring repeated vascular access over long periods of time utilize implantable vascular access catheter assemblies.
A vascular access catheter assembly may be implanted semi-permanently, with a distal end of the assembly remaining within the patient in contact with the vascular system while a proximal end remains external to the vasculature, for example in the form of a subcutaneously implanted port or an outdwelling proximal catheter access point. The proximal end is sealed when not in use to prevent blood loss and infections.
A common method of sealing an implanted catheter after use is to shut the catheter with a simple clamp. This method is often unsatisfactory because the repeated application of the clamp may weaken the walls of the catheter due to the stress placed on the walls at a single point. In addition, the pinched area of the catheter may not be completely sealed. Alternatively, pressure activated valves have been used at the proximal ends of catheters. Pressure activated valves seal rapidly and reliably without any operator input, do not affect catheter patency even after many opening and sealing cycles, and can tolerate the relatively low pressures and flow rates required for many applications for long periods of time. However, certain applications, such as infusion of contrast media for contrast-enhanced CT scanning require very high pressures and flow rates which may damage currently available pressure activated valves. It would be desirable to provide a pressure activated valve for a catheter with improved tolerance of high pressures and high flow rates.